https://vjudge.net/contest/256610#problem/Q
dp完全背包
https://vjudge.net/contest/256610#problem/P
深搜
https://vjudge.net/contest/258242#problem/I
记忆化
https://vjudge.net/contest/256610#problem/R
贪心或dp tree[i].pos - tree[i].hei > tree[i - 1].pos运算顺序的问题。。。。